Python to Replace Skechup Material to Cycles Material
Every object has a list of materials it uses in it's material_slots property, this is shown in the material properties, each slot contains the material used. By looping through this list you can change the material assigned to each slot.

I would setup a dictionary of old-to-new names to use for the conversion process.

import bpy

matnames = {
    'OldMaterial.01': 'NewMaterial.01',
    'OldMaterial.02': 'NewMaterial.02',
    'OldMaterial.03': 'NewMaterial.03',
    'OldMaterial.04': 'NewMaterial.04',
    'OldMaterial.05': 'NewMaterial.05',
    'OldMaterial.06': 'NewMaterial.06',
}

for obj in bpy.data.objects:
    for slot in obj.material_slots:
        slot.material = bpy.data.materials[matnames[slot.material.name]]